Two things stand out in this week's plea deal of Maria Butina, the Russian citizen branded by U.S. media as an "accused spy." The description of her offense by federal prosecutors doesn't mention any link to Russian intelligence services and the plea agreement says she's willing to cooperate with the U.S. authorities despite knowing she'll almost certainly be deported to Russia.

These peculiarities make Butina's a strange case.

The 30-year-old gun-rights activist and former graduate student at American University networked so inventively and tirelessly in Washington that she aroused the suspicion of U.S. counterintelligence and was arrested in July. She found herself in the media spotlight as an unlikely femme fatale until prosecutors walked back one of the original accusations — that she’d been willing to trade sex for getting ahead in her influence operation.

After spending five months in jail, Butina admitted having served as an agent of the Russian government without duly notifying the U.S. attorney general. That summoned memories of 10 people accused of being Russian sleeper agents in the U.S. in 2010, including Anna Chapman, who later became a minor celebrity in Russia, who pleaded guilty to the same offense. But the U.S. government's complaint against that group stated unequivocally that they had been sent to the U.S. to lie in wait until the Russian foreign intelligence service decided to use them.

No such accusation is being made in Butina's case. She's only admitted that she'd been working in the U.S. at the behest of Alexander Torshin, who resigned as deputy governor of the Russian central bank last month, and that she knew that he was coordinating his instructions for her with the Russian foreign ministry.

The Chapman group didn't plead guilty in exchange for cooperating with U.S. authorities; that would have made the intelligence assets traitors to Russia, the country to which they were deported immediately after sentencing. Instead, they were swapped for four people Russia had accused of working for Western intelligence services in Russia, including the victim of a botched poisoning in the U.K. this year, Sergey Skripal.

Butina, by contrast, promised to cooperate and will remain behind bars answering questions until at least mid-February, when the date of her sentencing may be determined in the next court hearing. It would have been hard for a Russian spy to agree to such terms knowing she'd be sent home: There, she'd almost certainly face prosecution for spilling the beans, or worse.

Butina isn’t being treated as a spy. If she were, any cooperation with the authorities would have been secret and she would have been offered protection, not warned bluntly of deportation — or she would have been swapped, like the 10 “sleepers.”

Her testimony in the next two months could change things, of course. But at this point, she's accused only of unofficial diplomacy and lobbying at conferences, dinners and other events that were by no means clandestine. She's admitted helping Torshin organize a back channel for the Russian government to the U.S. gun lobby and conservative politicians close to it.

The gun connection is important here. Both Torshin's and Butina's history with the gun-rights movement in Russia is well established. It's a hopeless cause there. Russia has a higher murder rate than any country in Europe or Asia except the Philippines. A recent poll showed that 89 percent of Russians oppose liberalizing gun sales. In a way, it was natural for the gun enthusiasts to seek allies in the U.S., given how few they had at home. They may have hoped that their joint cause would counterbalance the U.S. mistrust of President Vladimir Putin's regime.

Back channels of communication based on personal contacts and common interests are not inevitably malicious. U.S. presidents have repeatedly used them to avert crises and send private messages. I can easily imagine someone like Butina going unpunished during the Cold War; as a cub reporter in Moscow at the end of that era, I met Americans on similar unofficial missions who were all over town and weren’t jailed for it. Butina’s plea deal makes unnecessary any substantive discussion in court of how her actions could have harmed the U.S.

Ultimately, it was up to the U.S. authorities whether to prosecute Butina or let her hold overt meetings with conservatives, deeming them harmless to national security and perhaps even useful for fostering communication. They decided to prosecute, even though the court documents in Butina's case describe activities that were unrelated to the illegal hunt for information, which is how dictionaries define spying.

This decision now is unlikely to lead to momentous developments like the 2010 spy swap. But it does send a message to Americans that any Russian they meet could be a Kremlin agent. It’s easier not to take part in any such meetings than to ask whether their Russian counterpart has registered as a foreign lobbyist and filed the necessary paperwork with the attorney general. Perhaps that was the whole point of Butina’s optional prosecution — to let it be known that, after what the U.S. intelligence community considers massive Russian interference in the 2016 presidential election, no unofficial back channels to Russia will be tolerated.

If sending this message was indeed the point of building a case against Butina, it raises questions of how the American justice system is applied to citizens of countries with whom the U.S. is at odds.

This came up with the arrest last week of Meng Wanzhou, chief financial officer of the Chinese telecom giant Huawei. As my Bloomberg Opinion colleague Tyler Cowen wrote, “the West’s dirty little secret is that the rule of law works well only when tempered with a high degree of discretion.” The Huawei executive faces prosecution for allegedly conspiring to hoodwink banks to clear transactions linked to Iran, in violation of U.S. sanctions. Coming amid a trade war with China, Meng’s case sends multiple messages before the defendant gets her day in court.A crime is a crime, and in theory, all crimes should be prosecuted. But as a foreign observer, I think it’s fair to say that the discretion involved can be a sharp political instrument — and should be handled with care, lest the U.S. comes to be perceived as a country that weaponizes its laws against adversaries.

| Bloomberg News Leonid Bershidsky, Bloomberg News.

Leonid Bershidsky is a Bloomberg Opinion columnist covering European politics and business. He was the founding editor of the Russian business daily Vedomosti and founded the opinion website Slon.ru.